Production of black-and-white photographic pictures



Patented Dec. 5, 1939 PRODUCTION OF BLACK-AND-WHITE 'PHOTOGRAPHIC PICTURES Johannes Kleine, Dessau, and Gustav Wilmanns, Wolfen, Kreis Bitterfeld, Germany, assignors, by mesne assignments, to Agfa Ansco Corporation, Binghamton, N. Y., a corporation of Delaware No Drawing. Application November 18;, 1937, Serial No. 175,284. In Germany November 26,

1 Claim.

Our present invention relates to photography and more particularly to a photographic lightsensitive element yielding black-and-white pictures free from silver.

The production of photographic color pictures 5 which are free from silver by converting silver pictures into dyestuif pictures in a suitable manner is known. One process consists in producing a dyestufi picture by color forming development or by azo-coupling in a silver halide emul-' sion which contains dyestufi components. In the production of pictures by color forming development the dyestuff components may also be added to the developer. Insofar as the silver picture has not already been removed during the production of the dyestuff picture, as happens for instance in the silver bleaching out process, the silver picture is subsequently removed by means of a known solvent for silver.- It is an object of the present invention to provide a new and improved light-sensitivematerial capable of being converted into black-andwhite pictures by a process of color forming development. I

A further object is the provision of a photographic light-sensitive material comprising a silver halide emulsion containing a dyestuff component fast to diffusion and capable of forming a black dye with the oxidation product of a developer.

A further object is to provide a process by which black-and-white pictures'are obtainedfrom the aforementioned material by color forming development, which are free from silver.

Further objects will be apparent from the de- 35 tailed specification following hereafter.

This invention is based on the observation,

that black-and-white pictures free from silver may be obtained if there is added to the silver halide emulsion a dyestuff former which can be 40 converted into a black'dyestufi. The treatment of the silver halide emulsion for producing the 50 which thecoupling group is linked to a polynuclear radical, for instance 1,2-hydroxy-naphthoic acid-aminocarbazole; or amniophenyl-hydroxynaphthothiazole-sulfonic acid of the following formula soan i NHa Further there may be obtained components which are useful for the present purpose by linking several dyestuff components which individually formdifierent colors by color forming development. Thus it is, for instance, possible, to link up components which.yield blue, green,

- red dyes or components yielding complementary benzoylacetic-S-hydroxynaphthylamide of the following formula is a suitable component.

These dyestuff components may be developed with theaid of the usual color forming developers,- such as for instance para-diethylaminoaniline. A further increase in the absorption of the "resultant dyes may be obtained by using devel- P S which contain in their molecule the subdium. As described in U. S. patent application Ser. No. 72,718 filed April 4, 1936, there may be introduced into the dyestufi components groups which lend to the molecule of the dyestufi former substantive. character. As described in U. S.

' patent'application Ser. No. 90,726 filed July 15,

1936, the dyestuif components may be made fast to difiusion by introducing radicals of highly polymeric carboxylic acids or'derivatives thereof.

Furthermore, dyestufi components can be made fast to diifusion by introducing carbon chains. of more than carbon atoms as described in U. -S. patent application Ser. No. 94,340 filed August 5, 1936, polypeptide radicals as described in U. S. patent application Ser. No. 158,860 filed August 13, 1937, carbohydrate radicals as described in U. S. patent application Ser. No. 159,518 filed August 17, 1937, resin radicals as described in U. S. patent application Ser.

No. 164,499 filed September 18, 1937, and according to a further suggestion sterol, into the component. Finally dyestuif components fast to diffusion are obtained by combining several molecules for the color former to yield a chainlike molecule in which the reactive group of the color former recurs periodically.

The following compounds may be named by way of example: N-dodecyl-1.2-hydroxynaphthoic acid-aminocarbazole, dodecoylaminophenylhydroxynaphthothiazole sulfonic acid, 4,a,'hydroxyn'aphthoyl-4,p-nitrobenzoyl-monobromacetyl dichlorbenzidide.

If the dyestufi' components do not yield sumciently dark shades in the color forming development the dyestufi picture produced by the development may be converted into a darker dyestuif by subsequent treatment; for example, a dyestufi component may be used which yields on color forming development a dyestufl still containing one or more free amino groups which may be diazotized and coupled with azo-components; or, by action of diazo-components on dyestufi components having groups capable of coupling, such as NH2, OH, or the like, a deeper shade may be produced. In using-dye'stufi components for color forming development the picture may be produced by simple development or by reversal development, for instance by the process of U. S. patent applications Ser. No. 100,319 filed September 11, 1936 and Ser. No. 148,731

filed June 1'7, 1937. After the development the .silver is removed from the layer in a known manner, for example by means of Farmers Reducer.

Again, dyestufi components fast to diifusion may be used as described in U. S. patent application Ser. No. 10,704 filed March 12, .1935, the dyestuff picture being produced by azp-coupling. Also light-sensitive layers having, as described in U; S. patent application Ser. No. 111.- 250 filed November 17, 1936, color formers fast to difiusion are suitable in which the color picture is produced by destroying directly or indirectly the dyestu'ff former or the formed dyestuif overlying the silver picture.

The production of black-and-white pictures by a the .present invention is of particular advantage because the silver used for-producing the emulslon layer may be recovered substantially completely in the development installation. In view of the value of silver this point is of great commercial advantage.

.The invention is applicable in all cases in which black-and-white silver pictures are used, especially in the production of sound films. By, suitable choice of the dyestufi components the toning of the picture may be varied within wide limits. If desired a mixture of several dyestufi components may be used. The dyestufl' components may be contained in one or several layers which may be arranged on one or both sides of the support. Pictures to be viewed by transmitted light and those that are to be viewed by reflected light may be produced by the invention. The pictures obtained are-characterized by particularly fine grain and are suitable therefore for.

JOHANNES GUSTAV WILMANNS. 

